Novel Analytical and Numerical Methods in Heat Transfer Enhancement and Thermal Management

1Dipartimento di Ingegneria Industriale, Universita degli Studi di Napoli Federico II, 80125 Napoli, Italy 2Laboratoire de Modelisation et Simulation Multi Echelle, Equipe Transferts de Chaleur et de Matiere, Universite PARIS-EST, 77454 Marne-la-Vallee Cedex 2, France 3School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China 4Laboratory of Steam Boilers andThermal Plants, School of Mechanical Engineering, National Technical University of Athens, Zografou, 15780 Athens, Greece 5Mechanical and Aerospace Engineering Department, Rutgers, the State University of New Jersey, Piscataway, NJ 08854-8058, US

Pennes' bioheat equation vs. porous media approach in computer modeling of radiofrequency tumor ablation

[EN] The objective of this study was to compare three different heat transfer models for radiofrequency ablation of in vivo liver tissue using a cooled electrode and three different voltage levels. The comparison was between the simplest but less realistic Pennes' equation and two porous media-based models, i.e. the Local Thermal Non-Equilibrium (LTNE) equations and Local Thermal Equilibrium (LTE) equation, both modified to take into account two-phase water vaporization (tissue and blood). Different blood volume fractions in liver were considered and the blood velocity was modeled to simulate a vascular network. Governing equations with the appropriate boundary conditions were solved with Comsol Multiphysics finite-element code. The results in terms of coagulation transverse diameters and temperature distributions at the end of the application showed significant differences, especially between Pennes and the modified LTNE and LTE models. The new modified porous media-based models covered the ranges found in the few in vivo experimental studies in the literature and they were closer to the published results with similar in vivo protocol. The outcomes highlight the importance of considering the three models in the future in order to improve thermal ablation protocols and devices and adapt the model to different organs and patient profiles.This work was supported by the Spanish Ministerio de Economia, Industria y Competitividad under "Plan Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad", Grant No "RTI2018-094357-B-C21" and by the Italian Government MIUR Grant No "PRIN-2017F7KZWS".Tucci, C.; Trujillo Guillen, M.; Berjano, E.; Iasiello, M.; Andreozzi, A.; Vanoli, GP. (2021). Pennes' bioheat equation vs. porous media approach in computer modeling of radiofrequency tumor ablation. Scientific Reports. 11(1):1-13. https://doi.org/10.1038/s41598-021-84546-6S113111Chu, K. F. & Dupuy, D. E. Thermal ablation of tumours: biological mechanisms and advances in therapy. Nat. Rev. Cancer 14, 199–208 (2014).Brace, C. Thermal tumor ablation in clinical use. IEEE Pulse 2, 28–38 (2011).Pennes, H. H. Analysis of tissue and arterial blood temperatures in the resting human forearm. J. Appl. Physiol. 1, 93–122 (1948).Andreozzi, A., Brunese, L., Iasielllo, M., Tucci, C. & Vanoli, G. P. Modeling heat transfer in tumors: a review of thermal therapies. Ann. Biomed. Eng. 47, 676–693 (2019).Khaled, A.-R.A. & Vafai, K. The role of porous media in modeling flow and heat transfer in biological tissues. Int. J. Heat. Mass Transf. 46, 4989–5003 (2003).Rattanadecho, P. & Keangin, P. Numerical study of heat transfer and blood flow in two-layered porous liver tissue during microwave ablation process using single and double slot antenna. Int. J. Heat. Mass. Transf. 58, 457–470 (2013).Khanafer, K. & Vafai, K. The role of porous media in biomedical engineering as related to magnetic resonance imaging and drug delivery. Heat Mass Transf. 42, 939–953 (2006).Namakshenas, P. & Mojra, A. Microstructure-based non-Fourier heat transfer modeling of HIFU treatment for thyroid cancer. Comput. Meth. Prog Biol. 197, 105698 (2020).Wessapan, T. & Rattanadecho, P. Acoustic streaming effect on flow and heat transfer in porous tissue during exposure to focused ultrasound. Case. Stud. Therm. Eng. 21, 100670 (2020).Dutta, J., Kundu, B. & Yook, S. J. Three-dimensional thermal assessment in cancerous tumors based on local thermal non-equilibrium approach for hyperthermia treatment. Int. J. Therm. Sci. 159, 106591 (2021).Gunakala, S. R., Job, V. M., Sakhamuri, S., Murthy, P. V. S. N. & Chowdary, B. V. Numerical study of blood perfusion and nanoparticle transport in prostate and muscle tumours during intravenous magnetic hyperthermia. Alex Eng. J. 60, 859–876 (2021).Trujillo, M., Bon, J., Rivera, M. J., Burdio, F. & Berjano, E. Computer modelling of an impedance-controlled pulsing protocol for RF tumour ablation with a cooled electrode. Int. J. Hyperthermia 32, 931–939 (2016).Fukushima, T. et al. Randomized controlled trial comparing the efficacy of impedance control and temperature control of radiofrequency interstitial thermal ablation for treating small hepatocellular carcinoma. Oncology 89, 47–52 (2015).Cuenod, C. A. & Balvay, D. Perfusion and vascular permeability: Basic concepts and measurement in DCE-CT and DCE-MRI. Diagn. Interv. Imaging 94, 1187–1204 (2013).Keangin, P., Vafai, K. & Rattanadecho, P. Electromagnetic field effects on biological materials. Int. J. Heat Mass Transf. 65, 389–399 (2013).He, Y. et al. Finite element analysis of blood flow and heat transfer in an image-based human finger. Comput. Biol. Med. 38, 555–562 (2008).Gilbert, R. P. et al. Computing porosity of cancellous bone using ultrasonic waves II: The muscle, cortical, cancellous bone system. Math. Comput. Model. 50, 421–429 (2009).Wessapan, T. & Rattanadecho, P. Specific absorption rate and temperature increase in human eye subjected to electromagnetic fields at 900 MHz. ASME J. Heat Transf. 134, 911011–9110111 (2012).Effros, R. M., Lowenstein, J., Baldwin, D. S. & Chinard, F. P. Vascular and extravascular volumes of the kidney of man. Circ. Res. 20, 162–173 (1967).Taniguchi, H., Masuyama, M., Koyama, H., Oguro, A. & Takahashi, T. Quantitative measurement of human tissue hepatic blood volume by C15O inhalation with positron-emission tomography. Liver 16, 258–262 (1996).Yuan, P. Numerical analysis of temperature and thermal dose response of biological tissues to thermal non-equilibrium during hyperthermia therapy. Med. Eng. Phys. 30, 135–143 (2008).Andreozzi A, Brunese L, Iasiello M, Tucci C, Vanoli GP. Bioheat transfer in a spherical biological tissue: a comparison among various models. J Phys Conf Ser 2019;1224:012001. [19] Vafai K. Handbook of porous media. Boca Raton: CRC Press (2015).Goldberg, S. N. et al. Percutaneous radiofrequency tissue ablation: optimization of pulsed-radiofrequency technique to increase coagulation necrosis. J. Vasc. Interv. Radiol. 10, 907–916 (1999).Dobson EL, Warner GF, Finney CR, Johnston ME. The Measurement of Liver.Schwickert, H. C. et al. Quantification of liver blood volume: comparison of ultra short ti inversion recovery echo planar imaging (ulstir-epi), with dynamic 3d-gradient recalled echo imaging. Magn. Reson. Med. 34, 845–852 (1995).Stewart, E. E., Chen, X., Hadway, J. & Lee, T. Y. Correlation between hepatic tumor blood flow and glucose utilization in a rabbit liver tumor model. Radiology 239, 740–750 (2006).Solazzo, S. A., Ahmed, M., Liu, Z., Hines-Peralta, A. U. & Goldberg, S. N. High-power generator for radiofrequency ablation: larger electrodes and pulsing algorithms in bovine ex vivo and porcine in vivo settings. Radiology 242, 743–750 (2007).Song, K. D. et al. Hepatic radiofrequency ablation: in vivo and ex vivo comparisons of 15-gauge (G) and 17-G internally cooled electrodes. Br. J. Radiol. 88(1050), 20140497 (2015).Lee, J. M. et al. Radiofrequency ablation of the porcine liver in vivo: increased coagulation with an internally cooled perfusion electrode. Acad. Radiol. 13, 343–352 (2006).Haemmerich, D. et al. In vivo electrical conductivity of hepatic tumours. Physiol. Meas. 24, 251–260 (2003).Abraham, J. P. & Sparrow, E. M. A thermal-ablation bioheat model including liquid-to-vapor phase change, pressure- and necrosis-dependent perfusion, and moisture-dependent properties. Int. J. Heat. Mass Transf. 50, 2537–2544 (2007).Pätz, T., Kröger, T. & Preusser, T. Simulation of radiofrequency ablation including water evaporation. IFMBE Proc. 25/IV, 1287–1290 (2009).Trujillo, M., Alba, J. & Berjano, E. Relation between roll-off occurrence and spatial distribution of dehydrated tissue during RF ablation with cooled electrodes. Int. J. Hyperthermia 28, 62–68 (2012).Haemmerich, D. et al. Hepatic radiofrequency ablation with internally cooled probes: effect of coolant temperature on lesion size. IEEE Trans. Biomed. Eng. 50, 493–499 (2003).Chang, I. A. Considerations for thermal injury analysis for RF ablation devices. Biomed. Eng. Online 4, 3–12 (2010).Jacques, S., Rastegar, S., Thomsen, S. & Motamedi, M. The role of dynamic changes in blood perfusion and optical properties in laser coagulation tissue. IEEE J. Sel. Top Quant. Electron. 2, 922–933 (1996).Hall, S. K., Ooi, E. H. & Payne, S. J. Cell death, perfusion and electrical parameters are critical in models of hepatic radiofrequency ablation. Int. J. Hyperthermia 31, 538–550 (2015).Roetzel, W. & Xuan, Y. Bioheat equation of the human thermal system. Chem. Eng. Technol. 20, 268–276 (1997).Nakayama, A. & Kuwahara, F. A general bioheat transfer model based on the theory of porous media. Int. J. Heat Mass Transf. 51, 3190–3199 (2008).Vafai, K. Handbook of porous media (CRC Press, 2015).Woodard, H. Q. & White, D. R. The composition of body tissues. Br. J. Radiol. 59, 1209–1219 (1986).Crezee, J. & Lagendijk, J. J. W. Temperature uniformity during hyperthermia: the impact of large vessels. Phys. Med. Biol. 37, 1321–1337 (1992).Chen, M. M. & Holmes, K. R. Microvascular contributions in tissue heat transfer. Ann. NY Acad. Sci. 335, 137–150 (1980)

A Functional Variant of the Dimethylarginine Dimethylaminohydrolase-2 Gene Is Associated with Insulin Sensitivity

Background: Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase, which was associated with insulin resistance. Dimethylarginine dimethylaminohydrolase (DDAH) is the major determinant of plasma ADMA. Examining data from the DIAGRAM+ (Diabetes Genetics Replication And Meta-analysis), we identified a variant (rs9267551) in the DDAH2 gene nominally associated with type 2 diabetes (P =3610 25). Methodology/Principal Findings: initially, we assessed the functional impact of rs9267551 in human endothelial cells (HUVECs), observing that the G allele had a lower transcriptional activity resulting in reduced expression of DDAH2 and decreased NO production in primary HUVECs naturally carrying it. We then proceeded to investigate whether this variant is associated with insulin sensitivity in vivo. To this end, two cohorts of nondiabetic subjects of European ancestry were studied. In sample 1 (n = 958) insulin sensitivity was determined by the insulin sensitivity index (ISI), while in sample 2 (n = 527) it was measured with a euglycemic-hyperinsulinemic clamp. In sample 1, carriers of the GG genotype had lower ISI than carriers of the C allele (67633 vs.79644; P = 0.003 after adjusting for age, gender, and BMI). ADMA levels were higher in subjects carrying the GG genotype than in carriers of the C allele (0.6860.14 vs. 0.5760.14 mmol/l; P = 0.04). In sample 2, glucose disposal was lower in GG carriers as compared with C carriers (9.364.1 vs. 11.064.2 mg6Kg 21 free fat mass6min 21; P = 0.009)

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation

Numerical study of mixed convection in a horizontal no parallel-plates channel with an unheated moving plate

Purpose–The purpose of this paper is to analyze the thermal and fluid dynamic behaviors of mixed convection in air because of the interaction between a buoyancy flow and a moving plate induced flow in a horizontal no parallel-plates channel to investigate the effects of the minimum channel spacing, wall heat flux, moving plate velocity and converging angle. Design/methodology/approach–The horizontal channel is made up of an upper inclined plate heated at uniform wall heat flux and a lower adiabatic moving surface (belt). The belt moves from the minimum channel spacing section to the maximum channel spacing section at a constant velocity so that its effect interferes with the buoyancy effect. The numerical analysis is accomplished by means of the finite volume method, using the commercial code Fluent. Findings–Results in terms of heated upper plate and moving lower plate temperatures and stream function fields are presented. The paper underlines the thermal and fluid dynamic differences when natural convection or mixed convection takes place, varying minimum channel spacing, wall heat flux, moving plate velocity and converging angle. Research limitations/implications–The hypotheses on which the present analysis is based are two-dimensional, laminar and steady state flow and constant thermo physical properties with the Boussinesq approximation. The minimum distance between the upper heated plate of the channel and its lower adiabatic moving plate is 10 and 20 mm. The moving plate velocity varies in the range 0-1 m/s; the belt moves from the right reservoir to the left one. Three values of the uniform wall heat flux are considered, 30, 60 and 120 W/m2, whereas the inclination angle of the upper plate is 2° and 10°. Practical implications–Mixed convection because of moving surfaces in channels is present in many industrial applications; examples of processes include continuous casting, extrusion of plastics and other polymeric materials, bonding, annealing and tempering, cooling and/or drying of paper and textiles, chemical catalytic reactors, nuclear waste repositories, petroleum reservoirs, composite materials manufacturing and many others. The investigated configuration is used in applications such as re-heating of billets in furnaces for hot rolling process, continuous extrusion of materials and chemical vapor deposition, and it could also be used in thermal control of electronic systems. Originality/value–This paper evaluates the thermal and velocity fields to detect the maximum temperature location and the presence of fluid recirculation. The paper is useful to thermal designers

A heat transfer analysis of axial and radial functionally-graded ceramic foams solar air receivers

Volumetric solar receiver are promising as heat transfer devices in concentrated solar power applications because they allow to reduce heat losses at the receiver entrance when compared to more conventional tubular receivers. Among various porous materials, ceramic foams have been shown to be promising because of their extended heat transfer area and effective thermal conductivity, especially when they are manufactured by considering variable morphologies thanks to modern techniques like additive manufacturing. In this contribution, porous media numerical simulations are presented for fluid flow and heat transfer in ceramic foams receiver with different porosity functions on either axial or radial directions, and also when porosity varies on both directions. Such simulations are performed by employing Beer-Lambert law to model radiative heat transfer, and a Gaussian distribution for the incoming radiation. Results are obtained by constraining the average porosity for the different cases, showing that graded foams allow to obtain more or less similar outflow temperatures, but with reduced heat losses at the receiver entrance and also with less uniform velocity profiles to promote heat convection in some critical points of the receive

Thermal and Fluid Dynamic Behavior of Symmetrically Heated Vertical Channels with Auxiliary Plate

Air natural convection in vertical channel configurations is strongly attractive in thermal design and control of devices. This is mainly due to its simplicity, no maintenance costs and reliability. This paper examines air natural convection in vertical channels with an auxiliary plate along the centerline. The channel is symmetrically heated and the walls are at uniform heat flux, whereas the auxiliary plate is either adiabatic or heated at uniform heat flux. The analysis is obtained for a two-dimensional steady state and laminar regime, and the fully elliptic equations are solved numerically by the control volume method on a finite I-shaped computational domain. Results in terms of stream function and temperature fields, velocity and temperature profiles inside the channel and pressure profiles along the centerline are given either for insulated auxiliary plate or for heated auxiliary plate. The adiabatic auxiliary plate along the centerline of the channel produces a chimney effect reduction of the channel while the heated auxiliary plate, at higher Ra values (105-106), provides an increase in the mass flow rate in the channel. Finally, two correlations between average channel Nusselt number, channel Rayleigh number, Ra* and dimensionless auxiliary plate height, h/L, are proposed. One correlation is for the channel with heated auxiliary plate and another is for the channel with unheated auxiliary plate. The channel Rayleigh number range is 102-105 and the dimensionless auxiliary plate height, h/L, is in the range [0,1

Natural Convection in Vertical Channels with an Auxiliary Plate

Research on natural convection in open channels is very extensive due to its role in many engineering applications such as thermal control of electronic systems. In this paper, a parametric analysis is carried out in order to add knowledge of heat transfer in air natural convection for a symmetrically heated vertical parallel plate channel with a central auxiliary heated or adiabatic plate. The two-dimensional steady-state problem is solved by means of the stream function-vorticity approach and the numerical solution is carried out by means of the control volume method Results are obtained for both a heated and unheated auxffary plate, for a Rayleigh number in the range 10(3)-10(6) for a ratio of the auxiliary plate height to the channel plate height equal to 0, 0.5 and 1 and for a ratio of the channel length to the channel gap in the range 5-15. Correlations for maximum wall temperatures and average channel Nusselt numbers are proposed